| Message ID | 20210710081722.1828-2-zhiyong.tao@mediatek.com |
|---|---|
| State | Changes Requested, archived |
| Headers | show |
| Series | Mediatek pinctrl patch on mt8195 | expand |
| Context | Check | Description |
|---|---|---|
| robh/checkpatch | success |
Hi, On Sat, Jul 10, 2021 at 4:17 PM Zhiyong Tao <zhiyong.tao@mediatek.com> wrote: > > This patch adds rsel define for mt8195. > > Signed-off-by: Zhiyong Tao <zhiyong.tao@mediatek.com> > --- > include/dt-bindings/pinctrl/mt65xx.h | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/include/dt-bindings/pinctrl/mt65xx.h b/include/dt-bindings/pinctrl/mt65xx.h > index 7e16e58fe1f7..f5934abcd1bd 100644 > --- a/include/dt-bindings/pinctrl/mt65xx.h > +++ b/include/dt-bindings/pinctrl/mt65xx.h > @@ -16,6 +16,15 @@ > #define MTK_PUPD_SET_R1R0_10 102 > #define MTK_PUPD_SET_R1R0_11 103 > > +#define MTK_PULL_SET_RSEL_000 200 > +#define MTK_PULL_SET_RSEL_001 201 > +#define MTK_PULL_SET_RSEL_010 202 > +#define MTK_PULL_SET_RSEL_011 203 > +#define MTK_PULL_SET_RSEL_100 204 > +#define MTK_PULL_SET_RSEL_101 205 > +#define MTK_PULL_SET_RSEL_110 206 > +#define MTK_PULL_SET_RSEL_111 207 > + Instead of all the obscure macros and the new custom "rsel" property, which BTW is not in the bindings, can't we just list the actual bias resistance of each setting? We could also migrate away from R1R0. Then we can specify the setting with the standard bias-pull-up/down properties [1]. Also, please ask internally if Mediatek could relicense all the header files that Mediatek has contributed under include/dt-bindings/pinctrl/ [2] to GPL-2.0 and BSD dual license. These files are part of the DT bindings and we really want them to be dual licensed as well, and not just the YAML files. Regards ChenYu [1] https://elixir.bootlin.com/linux/latest/source/Documentation/devicetree/bindings/pinctrl/pincfg-node.yaml#L37 [2] Note that a few files were contributed by other people > #define MTK_DRIVE_2mA 2 > #define MTK_DRIVE_4mA 4 > #define MTK_DRIVE_6mA 6 > -- > 2.18.0 > _______________________________________________ > Linux-mediatek mailing list > Linux-mediatek@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-mediatek
On Tue, 2021-07-13 at 15:17 +0800, Chen-Yu Tsai wrote: > Hi, > > On Sat, Jul 10, 2021 at 4:17 PM Zhiyong Tao <zhiyong.tao@mediatek.com> wrote: > > > > This patch adds rsel define for mt8195. > > > > Signed-off-by: Zhiyong Tao <zhiyong.tao@mediatek.com> > > --- > > include/dt-bindings/pinctrl/mt65xx.h | 9 +++++++++ > > 1 file changed, 9 insertions(+) > > > > diff --git a/include/dt-bindings/pinctrl/mt65xx.h b/include/dt-bindings/pinctrl/mt65xx.h > > index 7e16e58fe1f7..f5934abcd1bd 100644 > > --- a/include/dt-bindings/pinctrl/mt65xx.h > > +++ b/include/dt-bindings/pinctrl/mt65xx.h > > @@ -16,6 +16,15 @@ > > #define MTK_PUPD_SET_R1R0_10 102 > > #define MTK_PUPD_SET_R1R0_11 103 > > > > +#define MTK_PULL_SET_RSEL_000 200 > > +#define MTK_PULL_SET_RSEL_001 201 > > +#define MTK_PULL_SET_RSEL_010 202 > > +#define MTK_PULL_SET_RSEL_011 203 > > +#define MTK_PULL_SET_RSEL_100 204 > > +#define MTK_PULL_SET_RSEL_101 205 > > +#define MTK_PULL_SET_RSEL_110 206 > > +#define MTK_PULL_SET_RSEL_111 207 > > + > > Instead of all the obscure macros and the new custom "rsel" property, > which BTW is not in the bindings, can't we just list the actual bias > resistance of each setting? We could also migrate away from R1R0. > ==>Hi Chenyu, The rsel actual bias resistance of each setting: MTK_PULL_SET_RSEL_000:75K in PU, 75k in PD; MTK_PULL_SET_RSEL_001:10k in PU, 5k in PD; MTK_PULL_SET_RSEL_010:5k in PU, 75k in PD; MTK_PULL_SET_RSEL_011:4k in PU, 5K in PD; MTK_PULL_SET_RSEL_100:3k in PU, 75k in PD; MTK_PULL_SET_RSEL_101:2k in PU, 5K in PD; MTK_PULL_SET_RSEL_110:1.5k in PU, 75k in PD; MTK_PULL_SET_RSEL_111:1k in PU, 5k in PD. The rsel actual bias resistance is different between PU and PD. > Then we can specify the setting with the standard bias-pull-up/down > properties [1]. > > Also, please ask internally if Mediatek could relicense all the header > files that Mediatek has contributed under include/dt-bindings/pinctrl/ [2] > to GPL-2.0 and BSD dual license. These files are part of the DT bindings > and we really want them to be dual licensed as well, and not just the > YAML files. > ==> We will confirm it internally and reply it later. Thanks. > > Regards > ChenYu > > > [1] https://elixir.bootlin.com/linux/latest/source/Documentation/devicetree/bindings/pinctrl/pincfg-node.yaml#L37 > [2] Note that a few files were contributed by other people > > > #define MTK_DRIVE_2mA 2 > > #define MTK_DRIVE_4mA 4 > > #define MTK_DRIVE_6mA 6 > > -- > > 2.18.0 > > _______________________________________________ > > Linux-mediatek mailing list > > Linux-mediatek@lists.infradead.org > > http://lists.infradead.org/mailman/listinfo/linux-mediatek
On Thu, Jul 22, 2021 at 3:54 PM zhiyong tao <zhiyong.tao@mediatek.com> wrote: > > On Tue, 2021-07-13 at 15:17 +0800, Chen-Yu Tsai wrote: > > Hi, > > > > On Sat, Jul 10, 2021 at 4:17 PM Zhiyong Tao <zhiyong.tao@mediatek.com> wrote: > > > > > > This patch adds rsel define for mt8195. > > > > > > Signed-off-by: Zhiyong Tao <zhiyong.tao@mediatek.com> > > > --- > > > include/dt-bindings/pinctrl/mt65xx.h | 9 +++++++++ > > > 1 file changed, 9 insertions(+) > > > > > > diff --git a/include/dt-bindings/pinctrl/mt65xx.h b/include/dt-bindings/pinctrl/mt65xx.h > > > index 7e16e58fe1f7..f5934abcd1bd 100644 > > > --- a/include/dt-bindings/pinctrl/mt65xx.h > > > +++ b/include/dt-bindings/pinctrl/mt65xx.h > > > @@ -16,6 +16,15 @@ > > > #define MTK_PUPD_SET_R1R0_10 102 > > > #define MTK_PUPD_SET_R1R0_11 103 > > > > > > +#define MTK_PULL_SET_RSEL_000 200 > > > +#define MTK_PULL_SET_RSEL_001 201 > > > +#define MTK_PULL_SET_RSEL_010 202 > > > +#define MTK_PULL_SET_RSEL_011 203 > > > +#define MTK_PULL_SET_RSEL_100 204 > > > +#define MTK_PULL_SET_RSEL_101 205 > > > +#define MTK_PULL_SET_RSEL_110 206 > > > +#define MTK_PULL_SET_RSEL_111 207 > > > + > > > > Instead of all the obscure macros and the new custom "rsel" property, > > which BTW is not in the bindings, can't we just list the actual bias > > resistance of each setting? We could also migrate away from R1R0. > > > ==>Hi Chenyu, > The rsel actual bias resistance of each setting: > > MTK_PULL_SET_RSEL_000:75K in PU, 75k in PD; > MTK_PULL_SET_RSEL_001:10k in PU, 5k in PD; > MTK_PULL_SET_RSEL_010:5k in PU, 75k in PD; > MTK_PULL_SET_RSEL_011:4k in PU, 5K in PD; > MTK_PULL_SET_RSEL_100:3k in PU, 75k in PD; > MTK_PULL_SET_RSEL_101:2k in PU, 5K in PD; > MTK_PULL_SET_RSEL_110:1.5k in PU, 75k in PD; > MTK_PULL_SET_RSEL_111:1k in PU, 5k in PD. > > The rsel actual bias resistance is different between PU and PD. Thanks. Somehow I missed this when looking through the datasheet. This encoding is interesting. Since it doesn't make sense to have both pull-up and pull-down, even though the hardware seems capable of doing so, I suppose the intent is to support 75k or 5k for pull-down, and (75k, 10k, 5k, 4k, 3k, 2k, 1.5k, 1k) for pull-up? We could add these values to the binding so we could check for misuse. The range of values seems to also cover those supported by the alternative R0/R1 settings. The values for kprow[01] and kpcol[01] seem to be different though. We should get rid of the MTK_PUPD_SET_R1R0_* macros at the same time. They seem to be some magic values used with bias-pull-*, which is not how the properties should be used. At the same time, they overlap with mediatek,pull-* properties. It would be great if we could standardize on the generic pinconf properties, and also use real values that fit the requirements of the properties, i.e. using real resistance values. I'm not sure if it would make sense to enumerate which pins support which configurations though. Thanks ChenYu > > Then we can specify the setting with the standard bias-pull-up/down > > properties [1]. > > > > Also, please ask internally if Mediatek could relicense all the header > > files that Mediatek has contributed under include/dt-bindings/pinctrl/ [2] > > to GPL-2.0 and BSD dual license. These files are part of the DT bindings > > and we really want them to be dual licensed as well, and not just the > > YAML files. > > > > ==> We will confirm it internally and reply it later. > > Thanks. > > > > Regards > > ChenYu > > > > > > [1] https://elixir.bootlin.com/linux/latest/source/Documentation/devicetree/bindings/pinctrl/pincfg-node.yaml#L37 > > [2] Note that a few files were contributed by other people > > > > > #define MTK_DRIVE_2mA 2 > > > #define MTK_DRIVE_4mA 4 > > > #define MTK_DRIVE_6mA 6 > > > -- > > > 2.18.0 > > > _______________________________________________ > > > Linux-mediatek mailing list > > > Linux-mediatek@lists.infradead.org > > > http://lists.infradead.org/mailman/listinfo/linux-mediatek >
On Thu, Jul 29, 2021 at 4:23 PM zhiyong.tao <zhiyong.tao@mediatek.com> wrote: > > On Mon, 2021-07-26 at 16:02 +0800, Chen-Yu Tsai wrote: > > On Thu, Jul 22, 2021 at 3:54 PM zhiyong tao <zhiyong.tao@mediatek.com > > > wrote: > > > > > > On Tue, 2021-07-13 at 15:17 +0800, Chen-Yu Tsai wrote: > > > > Hi, > > > > > > > > On Sat, Jul 10, 2021 at 4:17 PM Zhiyong Tao < > > > > zhiyong.tao@mediatek.com> wrote: > > > > > > > > > > This patch adds rsel define for mt8195. > > > > > > > > > > Signed-off-by: Zhiyong Tao <zhiyong.tao@mediatek.com> > > > > > --- > > > > > include/dt-bindings/pinctrl/mt65xx.h | 9 +++++++++ > > > > > 1 file changed, 9 insertions(+) > > > > > > > > > > diff --git a/include/dt-bindings/pinctrl/mt65xx.h b/include/dt- > > > > > bindings/pinctrl/mt65xx.h > > > > > index 7e16e58fe1f7..f5934abcd1bd 100644 > > > > > --- a/include/dt-bindings/pinctrl/mt65xx.h > > > > > +++ b/include/dt-bindings/pinctrl/mt65xx.h > > > > > @@ -16,6 +16,15 @@ > > > > > #define MTK_PUPD_SET_R1R0_10 102 > > > > > #define MTK_PUPD_SET_R1R0_11 103 > > > > > > > > > > +#define MTK_PULL_SET_RSEL_000 200 > > > > > +#define MTK_PULL_SET_RSEL_001 201 > > > > > +#define MTK_PULL_SET_RSEL_010 202 > > > > > +#define MTK_PULL_SET_RSEL_011 203 > > > > > +#define MTK_PULL_SET_RSEL_100 204 > > > > > +#define MTK_PULL_SET_RSEL_101 205 > > > > > +#define MTK_PULL_SET_RSEL_110 206 > > > > > +#define MTK_PULL_SET_RSEL_111 207 > > > > > + > > > > > > > > Instead of all the obscure macros and the new custom "rsel" > > > > property, > > > > which BTW is not in the bindings, can't we just list the actual > > > > bias > > > > resistance of each setting? We could also migrate away from R1R0. > > > > > > > > > > ==>Hi Chenyu, > > > The rsel actual bias resistance of each setting: > > > > > > MTK_PULL_SET_RSEL_000:75K in PU, 75k in PD; > > > MTK_PULL_SET_RSEL_001:10k in PU, 5k in PD; > > > MTK_PULL_SET_RSEL_010:5k in PU, 75k in PD; > > > MTK_PULL_SET_RSEL_011:4k in PU, 5K in PD; > > > MTK_PULL_SET_RSEL_100:3k in PU, 75k in PD; > > > MTK_PULL_SET_RSEL_101:2k in PU, 5K in PD; > > > MTK_PULL_SET_RSEL_110:1.5k in PU, 75k in PD; > > > MTK_PULL_SET_RSEL_111:1k in PU, 5k in PD. > > > > > > The rsel actual bias resistance is different between PU and PD. > > > > Thanks. Somehow I missed this when looking through the datasheet. > > This > > encoding is interesting. Since it doesn't make sense to have both > > pull-up and pull-down, even though the hardware seems capable of > > doing > > so, I suppose the intent is to support 75k or 5k for pull-down, and > > (75k, 10k, 5k, 4k, 3k, 2k, 1.5k, 1k) for pull-up? > > > > We could add these values to the binding so we could check for > > misuse. > > > > The range of values seems to also cover those supported by the > > alternative R0/R1 settings. The values for kprow[01] and kpcol[01] > > seem to be different though. > > > > We should get rid of the MTK_PUPD_SET_R1R0_* macros at the same time. > > They seem to be some magic values used with bias-pull-*, which is not > > how the properties should be used. At the same time, they overlap > > with > > mediatek,pull-* properties. > > > > It would be great if we could standardize on the generic pinconf > > properties, and also use real values that fit the requirements of the > > properties, i.e. using real resistance values. I'm not sure if it > > would make sense to enumerate which pins support which configurations > > though. > > > > > > Thanks > > ChenYu > > > > > The rsel actual bias resistance of each setting is different in > different IC. we think that the define "MTK_PULL_SET_RSEL_000" is more > common for all different IC. I see. I personally prefer having things clearly described. I can understand this might be an extra burden to support different chips with different parameters, though this should be fairly straightforward with lookup tables tied to the compatible strings. Let's see if Rob and Linus have anything to add. ChenYu > Thanks. > > > > > Then we can specify the setting with the standard bias-pull- > > > > up/down > > > > properties [1]. > > > > > > > > Also, please ask internally if Mediatek could relicense all the > > > > header > > > > files that Mediatek has contributed under include/dt- > > > > bindings/pinctrl/ [2] > > > > to GPL-2.0 and BSD dual license. These files are part of the DT > > > > bindings > > > > and we really want them to be dual licensed as well, and not just > > > > the > > > > YAML files. > > > > > > > > > > ==> We will confirm it internally and reply it later. > > > > > > Thanks. > > > > > > > > Regards > > > > ChenYu > > > > > > > > > > > > [1] > > > > https://elixir.bootlin.com/linux/latest/source/Documentation/devicetree/bindings/pinctrl/pincfg-node.yaml#L37 > > > > [2] Note that a few files were contributed by other people > > > > > > > > > #define MTK_DRIVE_2mA 2 > > > > > #define MTK_DRIVE_4mA 4 > > > > > #define MTK_DRIVE_6mA 6 > > > > > -- > > > > > 2.18.0 > > > > > _______________________________________________ > > > > > Linux-mediatek mailing list > > > > > Linux-mediatek@lists.infradead.org > > > > > http://lists.infradead.org/mailman/listinfo/linux-mediatek
On Thu, Jul 29, 2021 at 11:43 AM Chen-Yu Tsai <wenst@chromium.org> wrote: > On Thu, Jul 29, 2021 at 4:23 PM zhiyong.tao <zhiyong.tao@mediatek.com> wrote: > > The rsel actual bias resistance of each setting is different in > > different IC. we think that the define "MTK_PULL_SET_RSEL_000" is more > > common for all different IC. > > I see. I personally prefer having things clearly described. I can > understand this might be an extra burden to support different chips > with different parameters, though this should be fairly straightforward > with lookup tables tied to the compatible strings. > > Let's see if Rob and Linus have anything to add. Not much. We have "soft pushed" for this to be described as generic as possible, using SI units (ohms). But we also allow vendor-specific numbers in this attribute. Especially when reverse engineering SoCs that the contributor don't really have specs on (example M1 Mac). The intent with the SI units is especially for people like you folks working with Chromium to be able to use different SoCs and not feel lost to a forest of different ways of doing things and associated mistakes because vendors have hopelessly idiomatic pin configs. Yours, Linus Walleij
On Thu, Aug 5, 2021 at 7:02 AM Linus Walleij <linus.walleij@linaro.org> wrote: > > On Thu, Jul 29, 2021 at 11:43 AM Chen-Yu Tsai <wenst@chromium.org> wrote: > > On Thu, Jul 29, 2021 at 4:23 PM zhiyong.tao <zhiyong.tao@mediatek.com> wrote: > > > > The rsel actual bias resistance of each setting is different in > > > different IC. we think that the define "MTK_PULL_SET_RSEL_000" is more > > > common for all different IC. > > > > I see. I personally prefer having things clearly described. I can > > understand this might be an extra burden to support different chips > > with different parameters, though this should be fairly straightforward > > with lookup tables tied to the compatible strings. > > > > Let's see if Rob and Linus have anything to add. > > Not much. We have "soft pushed" for this to be described as generic > as possible, using SI units (ohms). But we also allow vendor-specific > numbers in this attribute. Especially when reverse engineering SoCs > that the contributor don't really have specs on (example M1 Mac). > > The intent with the SI units is especially for people like you folks working > with Chromium to be able to use different SoCs and not feel lost > to a forest of different ways of doing things and associated > mistakes because vendors have hopelessly idiomatic pin configs. I'll take that as "use SI units whenever possible and reasonable". Thanks. ChenYu
On Mon, Aug 16, 2021 at 6:48 PM zhiyong.tao <zhiyong.tao@mediatek.com> wrote: > > On Mon, 2021-08-16 at 14:10 +0800, Chen-Yu Tsai wrote: > > On Thu, Aug 5, 2021 at 7:02 AM Linus Walleij < > > linus.walleij@linaro.org> wrote: > > > > > > On Thu, Jul 29, 2021 at 11:43 AM Chen-Yu Tsai <wenst@chromium.org> > > > wrote: > > > > On Thu, Jul 29, 2021 at 4:23 PM zhiyong.tao < > > > > zhiyong.tao@mediatek.com> wrote: > > > > > The rsel actual bias resistance of each setting is different in > > > > > different IC. we think that the define "MTK_PULL_SET_RSEL_000" > > > > > is more > > > > > common for all different IC. > > > > > > > > I see. I personally prefer having things clearly described. I can > > > > understand this might be an extra burden to support different > > > > chips > > > > with different parameters, though this should be fairly > > > > straightforward > > > > with lookup tables tied to the compatible strings. > > > > > > > > Let's see if Rob and Linus have anything to add. > > > > > > Not much. We have "soft pushed" for this to be described as generic > > > as possible, using SI units (ohms). But we also allow vendor- > > > specific > > > numbers in this attribute. Especially when reverse engineering SoCs > > > that the contributor don't really have specs on (example M1 Mac). > > > > > > The intent with the SI units is especially for people like you > > > folks working > > > with Chromium to be able to use different SoCs and not feel lost > > > to a forest of different ways of doing things and associated > > > mistakes because vendors have hopelessly idiomatic pin configs. > > > > I'll take that as "use SI units whenever possible and reasonable". > > ==> so It doesn't need to change the define, is it right? > we will keep the common define. Actually I think it would be possible and reasonable to use SI units in this case, since you are the vendor and have the resistor values to implement the support. Having different sets of values for different chips is nothing out of the ordinary. We already have to account for different number of pins and different pin functions. That is what compatible strings are for. Now if you have _many_ different sets of values within the same chip, that could make things more difficult. However the clearness of having the real values visible in the device tree would likely benefit both software and hardware engineers outside of Mediatek. That is what we should be aiming for. Regards ChenYu
On Mon, Aug 16, 2021 at 5:38 PM Chen-Yu Tsai <wenst@chromium.org> wrote: > On Mon, Aug 16, 2021 at 6:48 PM zhiyong.tao <zhiyong.tao@mediatek.com> wrote: > > > I'll take that as "use SI units whenever possible and reasonable". > > > > ==> so It doesn't need to change the define, is it right? > > we will keep the common define. > > Actually I think it would be possible and reasonable to use SI units > in this case, since you are the vendor and have the resistor values > to implement the support. Having different sets of values for different > chips is nothing out of the ordinary. We already have to account for > different number of pins and different pin functions. That is what > compatible strings are for. I fully agree with Chen-Yu's analysis here. Zhiyong can you make an attempt to use SI units (Ohms) and see what it will look like? I think it will look better for users and it will be less risk to make mistakes. Yours, Linus Walleij
On Tue, Aug 17, 2021 at 10:21 AM zhiyong.tao <zhiyong.tao@mediatek.com> wrote: > > On Tue, 2021-08-17 at 01:00 +0200, Linus Walleij wrote: > > On Mon, Aug 16, 2021 at 5:38 PM Chen-Yu Tsai <wenst@chromium.org> > > wrote: > > > On Mon, Aug 16, 2021 at 6:48 PM zhiyong.tao < > > > zhiyong.tao@mediatek.com> wrote: > > > > > I'll take that as "use SI units whenever possible and > > > > > reasonable". > > > > > > > > ==> so It doesn't need to change the define, is it right? > > > > we will keep the common define. > > > > > > Actually I think it would be possible and reasonable to use SI > > > units > > > in this case, since you are the vendor and have the resistor values > > > to implement the support. Having different sets of values for > > > different > > > chips is nothing out of the ordinary. We already have to account > > > for > > > different number of pins and different pin functions. That is what > > > compatible strings are for. > > > > I fully agree with Chen-Yu's analysis here. > > > > Zhiyong can you make an attempt to use SI units (Ohms) and see > > what it will look like? I think it will look better for users and it > > will > > be less risk to make mistakes. > > > > Yours, > > Linus Walleij > > Hi Linus & chen-yu, > > The rsel actual bias resistance of each setting is different in > different IC. For example, in mt8195, the rsel actual bias resistance > setting like as: > MTK_PULL_SET_RSEL_000:75K in PU, 75k in PD; > MTK_PULL_SET > _RSEL_001:10k in PU, 5k in PD; > MTK_PULL_SET_RSEL_010:5k in PU, 75k in > PD; > MTK_PULL_SET_RSEL_011:4k in PU, 5K in PD; > MTK_PULL_SET_RSEL_100:3k in > PU, 75k in PD; > MTK_PULL_SET_RSEL_101:2k in PU, 5K in PD; > MTK_PULL_SET_RSE > L_110:1.5k in PU, 75k in PD; > MTK_PULL_SET_RSEL_111:1k in PU, 5k in PD. > > but in mt8192, the rsel actual bias resistance setting like as: > MTK_PULL_SET_RSEL_000:75K in PU, 75k in PD; > MTK_PULL_SET_RSEL_001:3k in PU, 5k in PD; > MTK_PULL_SET_RSEL_010:10k in PU, 75k in PD; > MTK_PULL_SET_RSEL_011:1k in PU, 5K in PD; > > Can you help me to provide a suggestion common define for the all > different IC? > It seems that we should add a new define, if we upstream a new IC > pinctrl driver in the future. I assume you mean the macros used in the device tree? The point of using SI units is to get rid of the macros. Instead of: bias-pull-up = <MTK_PULL_SET_RSEL_000>; and bias-pull-down = <MTK_PULL_SET_RSEL_011>; We want: bias-pull-up = <75000>; and bias-pull-down = <5000>; And the pinctrl driver then converts the real values in the device tree into register values using some lookup table. The DT schema could then enumerate all the valid resistor values, and get proper validity checking. Now if you really wanted to keep some symbols for mapping hardware register values to resistor values, you could have #define MT8192_PULL_UP_RSEL_001 75000 #define MT8192_PULL_DOWN_RSEL_001 5000 or have them all named MTK_PULL_{UP,DOWN}_RSEL_NNN, but split into different header files, one per SoC. Personally I think having the macros is a bad idea if proper values are available. It just adds another layer of indirection, and another area where errors can creep in. Regards ChenYu
On Tue, Aug 17, 2021 at 9:51 AM zhiyong.tao <zhiyong.tao@mediatek.com> wrote: > In one chip, If GPIO is different, the MTXXXX_PULL_UP_RSEL_001 may > means different actual bias resistance setting. > > For example, > > KPROW IO > Paramters Descriptions Min Typ Max > UNIT > Rpd Input pull-down resistance 40 75 190 Kohm > Rpu Input pull-up resistance 40 75 190 Kohm > Rpd Input pull-down resistance 0.8 1.6 2 Kohm > Rpu Input pull-up resistance 0.8 1.6 2 Kohm This is exactly why we should try to use SI units in the device tree. I assume that the software can eventually configure which resistance it gets? The electronics people will say make sure it is pulled down by around 80 kOhm, they can put that on the device tree and your code can say, "hm 40 < 80 < 190 this is OK" and let the value pass. We do not define these exact semantics, it is up to the driver code to decide what to do with the Ohm value 80000 in this case, but it makes perfect sent for me to let it pass and fail if someone for example requests 20 kOhm, or at least print a helpful warning: dev_warn(dev, "the requested resistance %d is out of range, supported range %d to %d kOhm\n", val, low, high); This is what makes the SI units really helpful for people writing device trees: solve real integration tasks and make it easy to do the right thing. Yours, Linus Walleij
On Wed, Aug 18, 2021 at 4:09 AM Linus Walleij <linus.walleij@linaro.org> wrote: > > On Tue, Aug 17, 2021 at 9:51 AM zhiyong.tao <zhiyong.tao@mediatek.com> wrote: > > > In one chip, If GPIO is different, the MTXXXX_PULL_UP_RSEL_001 may > > means different actual bias resistance setting. > > > > For example, > > > > KPROW IO > > Paramters Descriptions Min Typ Max > > UNIT > > Rpd Input pull-down resistance 40 75 190 Kohm > > Rpu Input pull-up resistance 40 75 190 Kohm > > Rpd Input pull-down resistance 0.8 1.6 2 Kohm > > Rpu Input pull-up resistance 0.8 1.6 2 Kohm > > This is exactly why we should try to use SI units in the device tree. > I assume that the software can eventually configure which resistance > it gets? > > The electronics people will say make sure it is pulled down by around > 80 kOhm, they can put that on the device tree and your code can > say, "hm 40 < 80 < 190 this is OK" and let the value pass. > > We do not define these exact semantics, it is up to the driver code > to decide what to do with the Ohm value 80000 in this case, but > it makes perfect sent for me to let it pass and fail if someone > for example requests 20 kOhm, or at least print a helpful warning: > > dev_warn(dev, "the requested resistance %d is out of range, supported > range %d to %d kOhm\n", > val, low, high); > > This is what makes the SI units really helpful for people writing device > trees: solve real integration tasks and make it easy to do the right thing. I think this makes a lot of sense. The driver could select the closest setting. And from what Zhiyong mentioned offline, the resistor values aren't exact as specified in the datasheet. I suppose this is expected with any electronics. So the hardware integration will say to pull up or down by some value, and the driver will do its best to fulfill that request. That precludes DT schema checking for the values used, but I think that is a good compromise. Zhiyong also mentioned that some of their downstream integrators might not be able to deal with actual values, and would prefer symbols tied to specific RSEL values. I think that would be doable together using some _magic_ values, but I would prefer not to if it were avoidable. Regards ChenYu
diff --git a/include/dt-bindings/pinctrl/mt65xx.h b/include/dt-bindings/pinctrl/mt65xx.h index 7e16e58fe1f7..f5934abcd1bd 100644 --- a/include/dt-bindings/pinctrl/mt65xx.h +++ b/include/dt-bindings/pinctrl/mt65xx.h @@ -16,6 +16,15 @@ #define MTK_PUPD_SET_R1R0_10 102 #define MTK_PUPD_SET_R1R0_11 103 +#define MTK_PULL_SET_RSEL_000 200 +#define MTK_PULL_SET_RSEL_001 201 +#define MTK_PULL_SET_RSEL_010 202 +#define MTK_PULL_SET_RSEL_011 203 +#define MTK_PULL_SET_RSEL_100 204 +#define MTK_PULL_SET_RSEL_101 205 +#define MTK_PULL_SET_RSEL_110 206 +#define MTK_PULL_SET_RSEL_111 207 + #define MTK_DRIVE_2mA 2 #define MTK_DRIVE_4mA 4 #define MTK_DRIVE_6mA 6
This patch adds rsel define for mt8195. Signed-off-by: Zhiyong Tao <zhiyong.tao@mediatek.com> --- include/dt-bindings/pinctrl/mt65xx.h | 9 +++++++++ 1 file changed, 9 insertions(+)